The present invention relates to a motor-driven, manually guided implement for receiving a rotatable cutter tool.
Tool heads, especially for rapidly rotating cutter tools, such as with brush cutters, edgers, cut-off saws, etc., are constructed pursuant to light weight standards taking into consideration handling ability, low centrifugal forces, and the avoidance of vibration problems. With such tool heads, rapidly rotating tools such as blades or filament reels, in order to avoid imbalances, are oriented at right angles and centrally relative to the longitudinal axis of the tool shaft by means of a tool carrying mechanism. For this purpose, the tool carrying mechanism is provided with an engagement plate having a contact surface that is oriented perpendicular to the shaft axis and against which rests the cutter tool, which is thereby held perpendicular to the shaft axis. In addition, a centering shoulder is provided for the central orientation of the cutter tool relative to the axis of rotation. Due to the typically relatively large diameter of the engagement plate and of the centering shoulder relative to the diameter of the tool shaft, and due to the dynamic forces that thereby result at high speeds, a light weight construction for these components is particularly important.
Also to be taken into consideration is that especially with rapidly rotating blades, which accidentally come into contact with hard objects such as rocks or branches, high radial forces can occur between the cutter tool and the centering shoulder. These forces then lead to increased and undesired wear of the centering shoulder, of the cutter tool in the region of the centering shoulder, or even both components.
DE 195 42 144 A1 shows a known tool head, on the tool shaft of which is disposed a tool hub that is positively connected with the shaft and is embodied as a protection against twisting. Integrally embodied with the tool hub are a centering shoulder and a flange having a contact surface against which is aligned a cutter tool having a safety plate disposed between the cutter tool and the contact surface. This known tool hub is a massive, relatively large component having a high weight when embodied as a steel component. If the hub is made of aluminum, wear problems can occur at the centering shoulder, as a consequence of which the entire component must be replaced.
It is therefore an object of the present invention to provide a light weight tool head having a tool carrying mechanism that is resistant to wear.